The Norfolk Broads is a man-made National Park with over 125 miles of navigable lock-free waterways, and many of them are perfect for exploration by Kayak and S.U.P. You will need to purchase a short visit Toll licence. These are £7.80, valid for seven days and can be obtained online, https://www.broads-authority.gov.uk/boating/owning-a-boat/tolls/short-visit-toll/short-visit-outlets, or via The Broads Authority information centres in Norwich, Hoveton or Ludham. You can also purchase the tolls from various boat yards around The Broads and a full list of these can be found by visiting the website listed above.
More info on visiting The Broads, including detailed paddle routes can be found here: https://www.visitthebroads.co.uk/discover-the-broads/boating/canoe-kayak-sup